50 The Microscope. 



remarks in a recent work on microscopic objects are 

 so much in point that I will repeat them without 

 abridgment.* 



" The effect of polarized light is not only beautiful 

 to the eye, but of real use to the investigator of 

 tissues, and in the researches of the pathologist, for 

 by it the true structure of organic bodies may often 

 be made clear, when the ordinary white light has 

 failed to develop it." Here I may remark that a great 

 number of structures are not acted on by polarized 

 light; for instance, the butterfly's wing partly divested 

 of scales, remains simply transparent during the whole 

 revolution of the prism ; and useful information may 

 be gained by observing whether an object polarizes or 

 not j and this holds good alike of microscopic revela- 

 tions and those of the telescope. The writer continues, 

 " Hardly in a concise manner can the question be 

 answered which is so often asked, 'Why are these 

 objects so coloured, and what is polarized light?' 

 But I may briefly explain that rays of light reflected 

 from a body under special conditions, or transmitted 

 through certain transparent crystals, undergo such 

 change in their properties, that they are no longer 

 subject to the same effects of reflection and refraction 

 as before. 



" The common ray of light may be compared to 

 a glass rod, smooth and white, uniform in texture, 

 whilst the polarized ray is smooth on one side, rough 

 and dark on the other. How it becomes so requires 



* From "Objects for the Microscope," by L. Lane Clarke. 

 Groombridge and Sons, London. 



